Third Generation (3G) wireless networks support data rates enabling a broader range of bandwidth-intensive services, such as streaming media, as well as more sophisticated services, such as services incorporating location information, e.g., regional traffic and weather reports, geographically targeted advertisements, and the like. Applications providing such services are naturally amenable to multicast transmission. While many unicast scheduling algorithms currently exist, few multicast scheduling algorithms currently exist, and the multicast scheduling algorithms that do exist significantly limit data throughput of user terminals close to the base station.
One existing approach is to offer fairness among all user terminals in all groups by making sure data transmission can be received by all user terminals in all groups in the cellular region. This approach fixes the data transmission rate to a default value (assuming that there is always at least one user terminal at the edge of the cellular region) and transmits to multicast groups in the cellular region in a round-robin manner. Existing CDMA EvDO networks use this approach; however, this scheme is oblivious of signal strength of user terminals such that user terminals close to the base station only receive limited data throughput even though their signal strength affords the ability for them to receive much higher data throughput. This approach sacrifices multicast data throughput for fairness.
Another existing approach is to improve multicast data throughput by partitioning user terminals with similar channel conditions into different multicast groups; however, due to channel condition dynamics and significant signaling overhead associated with multicast group membership changes, such a solution is not practical.